feat: add Gleam language support via the Gleam compiler's bundled gleam lsp (#1765)

test/resources/repos/gleam/test_repo/.gitignore

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+build/

test/resources/repos/gleam/test_repo/gleam.toml

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+name = "test_repo"
+version = "1.0.0"
+
+[dependencies]
+gleam_stdlib = ">= 0.44.0 and < 2.0.0"

test/resources/repos/gleam/test_repo/manifest.toml

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+# Do not manually edit this file, it is managed by Gleam.
+#
+# This file locks the dependency versions used, to make your build
+# deterministic and to prevent unexpected versions from being included
+# in your application.
+#
+# You should check this file into your source control repository.
+
+packages = [
+  { name = "gleam_stdlib", version = "1.0.3", build_tools = ["gleam"], requirements = [], otp_app = "gleam_stdlib", source = "hex", outer_checksum = "1F543AFBA5D33DA493E6087F4E4C4F20D899411343512686C98A8ABB2963CF22" },
+]
+
+[requirements]
+gleam_stdlib = { version = ">= 0.44.0 and < 2.0.0" }

test/resources/repos/gleam/test_repo/src/calculator.gleam

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+import utils
+
+/// A simple calculator type.
+pub type Calculator {
+  Calculator(name: String)
+}
+
+/// Adds two integers and returns the result.
+pub fn add(a: Int, b: Int) -> Int {
+  a + b
+}
+
+/// Subtracts b from a.
+pub fn subtract(a: Int, b: Int) -> Int {
+  a - b
+}
+
+/// Multiplies two integers.
+pub fn multiply(a: Int, b: Int) -> Int {
+  a * b
+}
+
+/// Formats the result of an operation using the utils module (cross-file reference).
+pub fn format_result(label: String, value: Int) -> String {
+  utils.format_output(label, value)
+}
+
+/// Returns the description of a calculator.
+pub fn describe(calc: Calculator) -> String {
+  "Calculator: " <> calc.name
+}
+
+/// Demonstrates calling add (same-file reference) and format_output (cross-file reference).
+pub fn demo() -> String {
+  let sum = add(7, 8)
+  utils.format_output("sum", sum)
+}

test/resources/repos/gleam/test_repo/src/diagnostics_sample.gleam

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+// This file intentionally contains a semantic error: `undefined_symbol` is not
+// defined anywhere, so the Gleam language server reports a diagnostic for it.
+pub fn broken() -> Int {
+  undefined_symbol
+}

test/resources/repos/gleam/test_repo/src/utils.gleam

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+import gleam/int
+import gleam/string
+
+/// Formats a label and integer value into a human-readable string.
+pub fn format_output(label: String, value: Int) -> String {
+  label <> ": " <> int.to_string(value)
+}
+
+/// Checks whether a string is non-empty.
+pub fn is_non_empty(s: String) -> Bool {
+  !string.is_empty(s)
+}